Field of the Invention
This invention relates generally to a mold for molding a part and, more particularly, to a mold for molding a thermoplastic part that includes a scaffolding structure having a plurality of support members defining open space for heating and cooling fluid flow.
Discussion of the Related Art
Injection molding of thermoplastic parts, for example, vehicle trim panels, is well established process in the industry. Molds and dies for injection molded parts are typically a solid machined piece of metal that includes a die cavity in which the part is formed. A typical injection molding cycle for a single run of one or more parts will include closing the mold, filling the mold with a thermoplastic material, such as pellets, heating the mold to the desired temperature, holding the pellets in the mold for some period of time so that the pellets melt and form the part, cooling the mold to solidify the part, and then ejecting the part from the mold.
Typically, heating the mold and cooling the mold are the longest parts of the cycle time, where cooling the mold is the most significant. To provide heating and cooling, the mold is typically drilled with channels in which a heating and cooling fluid, such as water, flows to heat the mold mass and cool the mold mass at the desired times during the injection molding cycle. Because a relatively large mass of metal needs to be heated and cooled to provide a uniform temperature distribution across the mold to effectively produce the part, the length of time to provide the heating and cooling for such a large mass is significant compared with how long it actually takes to form the part. The cycle time and thus system cost can thus be reduced by reducing the heating and cooling time of the molding cycle.